Light microscopy processing apparatus

ABSTRACT

A tissue processor provides a closed system for sequentially immersing light microscopy tissue specimens in treating fluids preparatory to embedding or in staining fluids. Treating or staining fluids, including paraffin, are drawn into the processing chamber by use of vacuum and are forced back to their respective containers by use of pressure and the specimens remain substantially stationary throughout the fluid treatment.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to tissue processing and more specifically toprocessing of tissue for light microscopy examination.

2. Description of the Prior Art

The processing of tissue for both electron and light microscopyexamination has been the subject of step-by-step improvement. Automaticprocessing of tissue for electron microscopy tissue processing has beenachieved as exemplified in applicant's U.S. Pat. Nos. 3,526,203 and3,771,490.

Automated apparatus for processing tissue for light microscopyexamination has been achieved as exemplified in the so-called"Technicon" tissue processor; however, there has been no successfulcompletely automatic system which would allow light microscopy tissuesto be processed under a completely automatic sequence and in an entirelyclosed system and without requiring substantial movement of thespecimens. The availability of a closed system is of critical importancein view of recently published Federal regulations governing handling ofhazardous vapors and fumes.

Representative prior art includes U.S. Pat. Nos. 3,227,130; 2,959,151;2,386,079; 2,341,198; 2,157,875; 2,959,151; 3,400,726; 2,681,298; and2,684,925.

A review of the prior art further reveals that treating fluids in lightmicroscopy processors are normally required to be recirculated. Theprocessing fluids may be manually returned to their respectivecontainers after use. Processing takes place in open or loosely coveredchambers which are not suitable for holding pressure or vacuumconditions. Many of the prior art light microscopy processors, e.g., theso-called Technicon tissue processor, also depend upon substantialmovement and dipping motions of the tissue specimens into opencontainers. Any motion of the specimens during processing, of course,tends to damage the specimens if carried to excess.

The prior art has also dealt with the problem of heating paraffin fluidsin containers, flow lines, valves, and the like. However, no prior artlight microscopy processor, so far as is known, has handled this problemsuccessfully in a closed, effectively sealed system, or with meansenabling the paraffin fluid to be reused. A fluid flow stainer usefulonly for staining has been marketed by Lipshaw Manufacturing Company ofDetroit, Mich. This apparatus recirculates staining fluids with apressure-vacuum system applied to the staining fluid containers but itis not useful for processing tissue, does not provide a pressure vesseltype chamber, and cannot handle paraffin.

In summary, the prior art in its present state does not embody apractical, reliable and automatic type of processor useful primarily forprocessing, including use of melted paraffin, but adapted to staininglight microscopy tissue specimens with a mimimum amount of handling ofthe tissue specimens, with maximum economy of the treating fluids, andin a closed system which substantially eliminates dangers from hazardoustreating fluid fumes.

SUMMARY OF THE INVENTION

The apparatus of the invention provides a plurality of containers oftreating fluids, including paraffin, which are drawn to a sealedprocessing chamber by vacuum and returned by pressure which is appliedto the chamber. The tissue specimens are confined in the processingchamber under sealed cover and remain stationary during processing.Fixation, processing, and clearing solutions are directed to theprocessing chamber in a programmed sequence. The paraffin containers arearranged in immediate proximity to the processing chamber whichsubstantially reduces the heating problem and the paraffin in thesecond, less contaminated, paraffin container can, at any time, bepumped to the first container, the first container paraffin pumped towaste and the second container paraffin replaced in order to minimizeparaffin consumption. The apparatus is unified in a table mountedcabinet.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the invention processing apparatusembodied in a cabinet for table top support.

FIG. 2 is a somewhat schematic diagram of the invention showingparticularly a preferred fluid flow configuration based on use of vacuumand pressure applied to a sealed processing chamber.

FIG. 3 is a partial side view showing the processing chamber coupled toone of the processing solution containers through a rotary valvemechanism by appropriate fluid lines in accordance with the invention,other containers being similarly coupled.

FIG. 4 is a side view to illustrate the shape of processing solutioncontainer found useful for the subsantially sealed, fumeless operationof the invention.

FIG. 5 is a perspective view of a tissue processing and embeddingreceptacle used in the present invention.

FIG. 6 is a side cross-sectional view of the invention processingchamber showing a processing receptacle basket in partial cutaway viewrevealing installed tissue processing receptacles.

FIG. 7 is a rear cutaway view of the invention processing chamber andliquid paraffin containers.

FIG. 8 is a front view of the left side control panel used in theinvention.

FIG. 9 is a front view of the right side invention control panel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In reference to the drawings, a suitable perforated tissue receptacle 25for holding the tissue specimens to be processed is generally shown inFIG. 5 and is known in the art as a TIMS tissue receptacle. For a moredetailed description of TIMS tissue receptacles used in paraffinembedding histological tissue sections, reference is made to U.S. Pat.No. 3,411,185 issued on Nov. 19, 1968, and entitled "CompositeHistologic Tissue Receptacle." A typical receptacle has a removablecover and may contain one or more tissue samples in the receptacle bodycavity to be fixed, dehydrated, cleared, and paraffin embedded prior tobeing thin sectioned on a rotary microtome. Fluids pass throughperforations in the receptacle which is made of materials inert to thefluids.

As previously mentioned, the light microscopy tissue processor of theinvention is directed to a closed system which allows a plurality ofperforated tissue receptacles 25 to be processed simultaneously in asealed chamber according to a scheduled time sequence, through variousselected processing solutions among which are fixatives, dehydrants,clearing solutions and liquid paraffin. The particular solutions usedand the particular time sequence for each may vary according todifferent programs. Also, staining solutions may be programmed forexchange between the chamber and the containers when holding stainingfluids.

Referring now to FIG. 1, an automatic light microscopy tissue processor10 according to a preferred embodiment includes a cabinet adapted fortable top support; a pair of laterally spaced, upper rearward controlcompartments 11, 16; a lower, centrally and forwardly located tissueprocessing chamber 12; a pair of lower, laterally and forwardly spacedheated liquid paraffin containers 13, 14; a plurality of solutioncontainers 15 in an upper central rearwardly compartment for holding theselectively communicated fluids for processing chamber 12; timingcontrols 17; and appropriate container signal lights 18.

Processing chamber 12 remains stationary and includes a tiltable lid 21having a window 22. Lid 21 has a hinge 26 and is secured to processingchamber 12 in a substantially air tight, sealed relation by appropriatelatches 28 and a rim 27 and gaskets 29 (indicated in FIG. 6). Processingchamber 12 is adapted to receive a plurality of tissue processingreceptacles 25, best shown in FIG. 5, and more fully described in thementioned U.S. Pat. No. 3,411,185. As best illustrated in FIG. 6, abasket structure 30 having perforated sidewalls 32 receives saidreceptacles and supports a plurality of such tissue receptacles 25within processing chamber 12. Also shown in FIG. 6, is an appropriatepressure and vacuum inlet coupling 34 as well as fluid line coupling 35which communicate with the interior of said processing chamber 12. Asuitable rectangular perforate plate 24 provides weight sufficient toovercome the buoyancy of the tissue receptacles 25 and keeps themsubmerged during processing.

Referring now to FIG. 2, solution containers 15 are connected toprocessing chamber 12 by individual conduits 38 which communicate with arotary valve structure 39 and then through a common conduit 33 toelectrically operated valve 42 and from there directly into processingchamber 12. When solutions are returned to their containers, they simplyretrace the supply route in reverse. Rotary valves as such are known andwhile a single rotary valve as illustrated has many advantages, asolenoid valve at each container could be employed to achieve selectionand controlled fluid flow in conjunction with the unique paraffinrelated apparatus later described.

Water base solutions, such as Zenker's, formalin and water, areeffectively kept separated from oil base solutions such as Xylene, thecombination of which causes formation of an emulsion. Typically then,for the ten numbered solutions shown, the invention contemplates thatsolution one will be fixative, e.g., Zenker's or formalin; solutions twothrough six will comprise various percentages of alcohol fordehydrating; and solutions seven and eight are Xylene for clearing.Further solutions such as Xylene and alcohol will be contained incontainers nine and ten for purposes of cleaning processing chamber 12following a completed processing sequence and withdrawal of processedtissue specimens from chamber 12.

The following table shows a series of processing and cleaning solutionswhich might typically be used according to the invention:

    __________________________________________________________________________              Container No. Solution                                              __________________________________________________________________________              1             Zenker's (or formalin)                                          2             70% Alcohol                                                     3             80% Alcohol                                                     4             95% Alcohol                                           Processing                                                                              5             Absolute Alcohol                                      Cycle     6             Absolute Alcohol                                                7             Xylene                                                          8             Xylene                                                          Paraffin I                                                                    Paraffin II                                                                   9             Xylene                                                Cleaning  10            Absolute Alcohol                                      Cycle     Additional water rinses                                                       manually done, if desired                                           __________________________________________________________________________

Referring now to FIG. 3, a typical processing solution container 15 of acommercially available shape as in FIG. 4, conduit 38, rotary valve 39made up of rotatable plate 41 and fixed plate 43, common conduit 33,valve 42 and processing chamber 12 are shown in operative assembly. Asuitable swivel connection 40 allows the movable rotary valve plate 41of rotary valve 39 to rotate. While FIG. 3 only illustrates the fluidpath for only one solution container 15, it should be clear from FIG. 2that there are in fact ten solution containers, all of which feed intorotary valve 39 and then into common conduit 33. Container 15 of FIG. 3is shown having a fitting 54 which will facilitate rapid changing ofsolution containers. A tube 58 communicates with the bottom of container15 to drain the entire contents, if desired, during processing.

As previously mentioned, the invention processor is adapted to beoperated so that all solution admission, solution retention and solutiondrainage takes place in automatic or alternately, manual timed sequenceand in a substantially closed system. Selective application of airpressure and partial vacuum to the sealed processing chamber 12 inconjunction with operation of valve 42, etc., enables rapid transfer ofprocessing solutions from containers 15 to chamber 12 and back tocontainers 15 again.

With specific reference again to FIG. 2 a combined vacuum and pressuresystem 60 is shown in dashed lines and comprises a pressure pump 61having means for providing pressure as well as partial vacuum asindicated and remotely operable valve means 64, 65, for selectingwhether vacuum or pressure is applied to an air line 70 communicatingwith processing chamber 12.

Referring again to FIG. 3, solution admission and drainage from chamber12 and fluid measurement is controlled by selective application ofpressure and partial vacuum to the chamber 12 via the air line 70 inconjunction with timed operation of the remotely operable rotary valve39 and remotely operable valve 42. Air line 70 preferably connects tothe interior of chamber 12 at a relatively high location near the coveras illustrated which avoids entry of the solutions into .[.chamber 12.]..Iadd.line 70.Iaddend.. By creating a timed partial vacuum in chamber12, a selected fluid is drawn into the chamber, and by pressurizingchamber 12 the fluid is expelled from the chamber. Reference will nextbe made to FIG. 2 for a discussion of one pressure, vacuum and rotaryvalve arrangement useful in the invention, and then to FIGS. 2 and 7 fora description of liquid paraffin flow to and from chamber 12 accordingto the invention. Since rotary valves are known, no detailed descriptionof valve 39 is deemed necessary.

Referring again to FIG. 2, in a "pump in" cycle fluid flow to processingchamber 12 from any given solution container 15 or paraffin containers13 or 14 is effected by creating a timed, partial vacuum in the sealedprocessing chamber 12. In the diagram shown, this is accomplished byactuating valve 64 to enable air to flow between F and B, by energizingpump 61, and by actuating valve 65 to enable air to flow between D and Eon a timed schedule. Simultaneous with the application of a partialvacuum to chamber 12, rotary valve 39 rotates to provide a path throughvalve 39 for the desired solution to flow through valve 39, into conduit33, through valve 42 and on into processing chamber 12. As an example,to move a measured quantity of solution number one to chamber 12, rotaryvalve 39 is energized and plate 41 is rotated until the line 38 fromcontainer number one lines up with the conduit 33 opening and valve 42is opened on a timed schedule. Air drawn from chamber 12 during suchvacuum cycle is expelled to atmosphere by means of a filtered exhaust 69which is located so as to have its fumes withdrawn as illustrated inFIG. 2. Alternatively, in a "pump out" cycle to effect fluid flow backto a selected solution container 15, chamber 12 is pressurized aboveatmosphere by actuating valve 64 to permit air to flow between A and B,and by actuating valve 65 to permit air to flow between D and F. Air istaken into pump 61 by means of an intake opening at A. Suitably, valve42 and rotary valve 39 assume the same open position as on the vacuum orpump in cycle to enable fluid to flow back into the appropriatecontainer 15. The fluid and air line valves normaly remain closed whilea pump in or pump out cycle is not in progress with the exception of theair line valves used during vacuum and pressurized agitation laterdescribed. Valve 42 is located immediately adjacent the rear wall and isclosely coupled to chamber 12 and is positioned proximate the bottomwall of chamber 12. This position facilitates entry and drainage offluids. Also, by keeping valve 42 closed during use of paraffin, thereis a minimum opportunity for the paraffin to block valve 42.

Referring again to FIG. 3, the previously referred to solutioncontainers 15 (with operating numbers 1 through 10) have respective caps55 for refilling the containers. Suitable air vents 56, indicated bydashed lines, are provided in each cap 55, but are preferably keptextremely small so as to limit any admission of moisture. Caps 55 mayalso be provided with dessicant material 57 to keep certain solutionse.g., absolute alcohol substantially free from moisture. As illustratedin FIGS. 1 and 2, fluid vapors vented to atmosphere during normaloperation of processor 10 are collected by a fume manifold 74 serving asa top portion of housing 11 and are exhausted by an appropriate fan 74a.A suitable trap .Iadd.in .Iaddend.line 70 filters fumes, et cetera.

Referring next to FIG. 7, liquid paraffin is stored in two heated andtemperature controlled, laterally spaced containers 13 and 14 residingimmediately adjacent and on either side of processing chamber 12.Transport of liquid paraffin from either container 13 or 14 to chamber12 is preferably accomplished by use of valves 75, 75' which areillustrated in submersed positions immediately adjacent and near thebottom wall of chamber 12. Respective conduit means 62, 63 communicatevalves 75, 75' with chamber 12 as shown. This arrangement enables theheating elements 77, 77a (shown schematically in FIG. 2) which areintegral with paraffin container 13, 14 respectively to maintain thecorrect temperature in the liquid paraffin as well as in the respectivevalves 75, 75' and the conduits 62, 63. Thermostats 76, 76a and thermalfuses 76b, 76c maintain the desired temperature and prevent overheating.Valves 75, 75' may also be located externally of the respective paraffincontainers but should have close, i.e., minimal distance couplings bothto the paraffin containers 13, 14 and to chamber 12 and should be neartheir bottom walls.

It should be noted that the provision for two separate paraffin stagesas embodied by the invention enables substantially complete paraffinimpregnation of tissue specimens prior to paraffin embedding. While oneparaffin stage could be used, use of two paraffin stages is generallyconsistent with current tissue processing technique, although variationon the exact number of paraffin steps may occur between differenthistological technicians. Paraffin containers 13 and 14 may be formedsubstantially integral with processing chamber 12 separated only bycommon partitions 66. A lid 23 on each paraffin container 13 and 14 ishinged and may be periodically opened to replenish the supply ofparaffin, while respective manual drain means 81 may be used to drainthe used, impure paraffin. Paraffin containers 13 and 14 are notrequired to be pressure sealed but should preferably be closed toatmosphere contamination.

As will be described later, control means are provided in the inventionenabling transport of a body of liquid paraffin from one paraffincontainer to the opposite enabling impure paraffin used, say, in thenext sequential step following the last step of Xylene (solution 8 ofFIG. 2) to be periodically drained and replaced with less impureparaffin previously used in the final processing step. This enables asubstantially pure body of paraffin to be maintained for the lastprocessing step, but makes use, through an automatic "paraffin exchange"step, of slightly impure paraffin for the next to the last processingstep. Such exchange of paraffin is contemplated every sixth processingsequence.

Prior to discussing the programming sequence reference is again made toschematic diagram of FIG. 2 wherein note should be taken of the use of adual heating element to heat processing chamber 12. A first heatingelement 84, located in the sidewall of processing chamber 12 (see FIG.6), is adapted to gradually provide heat to said chamber 12 from thefirst processing step until the first paraffin step (after sequentialsolution 8 of FIG. 2) and is set by thermostat 85 and by thermal fuse 86to approach but not to exceed 42° C. Slight heating of chamber 12throughout the early tissue processing sequence, e.g., fixative,dehydrating, and clearing steps enables better solution penetration intothe tissue and also provides a pre-heated container prior to entry ofmelted paraffin. Temperature must be restricted during the steps of suchvolatile solutions as alcohol and Xylene. Once the first paraffin stepis reached, however, second heating element 89, located in the base ofprocessing chamber 12 (see FIG. 6) is adapted to be energized raisingthe temperature within chamber 12 to 62° C. It should be noted that thelag time for this necessary temperature rise need only be very short,e.g., 15 seconds, since chamber 12 approximates 62° C immediately priorto the first paraffin step. Thermal fuse 82 and thermostat 83 preventoverheating of chamber 12 during paraffin steps. While heaters 84 and 89are shown in a preferred location, alternate locations might be chosento achieve the desired result of even temperature throughout processingchamber 12. As seen in FIGS. 3 and 6, a third heating element 91 islocated adjacent the rear wall of chamber 12. Element 91 effectivelymaintains a suitable operating temperature on valve 42 and minimizesclogging by any paraffin which happens to enter the valve port adjacentchamber 12. Thermal fuse 92 and thermostat 93 prevent overheating ofchamber 12. The overall heating is also designed to maintain allparaffin carrying pipes at an above melting temperature.

As heretofore described, vacuum and pressure conditions are selectivelyapplied to the sealed processing chamber 12 and are effectively used totransport the various processing and cleaning solutions of the inventiontissue processor to and from the processing chamber. An advantageousfeature of the invention arrangement resides in its capacity to useremotely and electrically operated valves, heaters and the electricallyoperated air pump 61. Another advantage is the capacity to apply suchvacuum or alternating vacuum and pressure to said processing chamberwhile a selected solution is in said chamber, to enhance solutionpenetration into the tissue being processed. In addition, vacuum oralternating vacuum and pressure applied to solutions in chamber 12 mayresult in improved penetration of tissue in the receptacles installed inthe chamber due to trapped air bubbles being freed.

Referring again to FIG. 2, vacuum or alternating vacuum and pressureapplied to chamber 12 during processing of given solutions (includingparaffin) hereinafter referred to as an "agitation cycle" is preferablyconducted at periodic intervals, e.g., every 10 minutes while each ofselected processing solutions is in chamber 12. The term agitation isused in a loose sense to mean increasing tissue penetration by vacuum orpressure, releasing air bubbles, and the like. It has previously beenmentioned that air valves 64 and 65 and fluid valves 42 and 39 remainclosed while a given solution is not being pumped to or from chamber 12.To create a partial vacuum in chamber 12 for purposes of agitationvalves 64 and 65 are set to the previously described vacuum cyclepositions, and pump 61 is energized for a predetermined period of timeset by an agitator timer 104 (not shown on control panel). A vacuum of-22 p.p.s.i. may be exerted, for example. The invention alsocontemplates the use of a partial vacuum periodically during givensolution steps and a pressure during other solution steps. Pressure maybe applied by moving valves 64 and 65 to the respective pressure cyclepositions and energizing the electrically operated air pump 61. It isapparent that suitable programming of alternating pressure and vacuumagitation cycles or simply of intermittent vacuum cycles may be readilyaccomplished by stepping switches or logic circuitry well known to thoseskilled in the art.

The program logic and stepping control 100 employed by the presentinvention may comprise a suitable rotary stepping switch having a clockdrive, or preferably solid state logic circuitry. In any case, the logicor stepping mechanism involved is deemed well within the related art soas to not require detailed elaboration herein. The general type ofcircuitry required has been illustrated in FIG. 2 and is of the typegenerally described, for example, in prior U.S. Pat. No. 3,771,490. Inorder to illustrate typical operations of the described processingapparatus, however, the description will now briefly describe a seriesof controls and their preferred functions used by the invention.

Referring now to FIGS. 2, 8 and 9, an on-off switch 102 controls powerto the processor program and stepping control 100. The power ispreferably continuously supplied to paraffin bath heating elements 77and 77a via thermostats 76, 76a and thermal fuses 76b, 76c to maintainthe paraffin contained in baths 13, 14 above melting point even whileprocessor 10 is idle. Thus, the paraffin temperature is preferablyunaffected by operation of on-off switch 102. Switch 102 preferablycontains a suitable indicator lamp 107 to indicate to the operator thatthe processor is energized. Selective manual or automatic operation isprovided by a mode selector switch 111. For manual operation switch 109is employed and for automatic operation switch 110 is employed. Manualcontrol of sequential, i.e., step-by-step, processing steps is providedby push button switch 112 and which causes illumination of solutionsignal lights 18 (see also FIG. 1). Manual solution pumping in orpumping out cycles are controlled by switches 114 and 115, respectively,which govern vacuum and pressure cycles of the vacuum pressure system60. The signal lights 18 are preferably arranged to illuminate to halfintensity indicating which step the processor has reached, and to fullintensity whenever the respective solution is being pumped to or fromchamber 12. A level control switch 117 provides a choice between high,medium, and low solution levels in chamber 12 by controlling the lengthof time which pump 61 operates during a given solution pump-in orpump-out. Thus, processor 10 is adapted to handle either relativelylarge or small quantities of processing receptacles.

For determining the length of time the tissue samples are exposed toeach processing solution, a pair of manually set timers 120, 121,including hour and minute settings, are provided. Step duration selectorswitches 125 (see FIGS. 1 and 2) are located above each processingsolution container. Similar step duration selector switches 125' on leftcontrol panel 11 provide a similar function for the paraffin containers13, 14. Switches 125, 125' enable selection between times 120, 121 oralternately to zero time which causes the particular step to be skippedor to unlimited time which causes the particular solution to be pumpedin during automatic sequence but not pumped out. A time display 130informs the operator of elapsed time for each solution and automaticallyresets when the next solution is admitted to chamber 12. A manual timedisplay reset 131 is provided. A hold button 137 on control panel 16 isprovided and suitably connected to temporarily interrupt the timingsequence in case of emergency, et cetera.

Under an automatic mode of operation of the processor, solution pump-in,pump-out and stepping to the next solution step takes place in theappropriate preselected time sequence, throughout the designatedprocessing solution numbers 1 through 10 and including the two paraffinsteps hereinbefore described. The last paraffin step is preferablyadapted to stay in chamber 12 until the operator removes the processedtissue, reseals chamber 12 and manually begins a clean out cycle byoperating mode selector switch 111. Pump-out switch 115 is depresseduntil all of the paraffin in chamber 12 is pumped back into paraffinbath number 2. The clean out operation is started by depressing manualstep button 112 which effectively moves the system up to the nextsolution. Pump-in button 114 is depressed and held until a desiredamount of solution number 9, e.g., Xylene, is pumped into chamber 12.Chamber 12 is manually cleaned with Xylene solution and the excesssolution is vacuum removed in the clean out operation. Next, step button112 is depressed which moves the system up to solution number 10, e.g.,absolute alcohol. Button 114 is depressed and begins pumping solution 10into chamber 12. Button 114 is held until a desired level of solution 10is pumped into chamber 12 and is then released stopping the pumping.Chamber 12 is further cleaned manually. Once chamber 12 is cleaned, modeselector 111 can now be set to automatic and chamber 12 refilled withTIMS receptacles for processing another batch of tissue specimens placedtherein.

It is desirable to be able to remove the paraffin in paraffin chamber 13since it becomes contaminated after it is used several times. Onceremoved, the less used paraffin in container 14 can be pumped to chamber13 by using vacuum to draw the paraffin into chamber 12 and thenpressure to force it into container 13. The paraffin in chamber 13 isdrained out with the aid of manual drain 81 of chamber 13 and paraffinchamber 14 after being emptied is then charged with new paraffin.

In most processing applications, it is desirable to hold the tissue inthe receptacles in the No. 1 solution (e.g., Zenker's or formalin) forseveral hours prior to initiating an automatic timed solution processingsequence. For such purpose, a long delay timer 134 may be employed sothat the first solution may be admitted manually and the remainder ofthe particular program on an automatic basis after some predeterminedtime delay, such as in the order of 4 hours for short term runs or inthe order of 72 hours for weekend runs. Suitably, an additional switchapplies the delay timer 134 to that solution step.

While a wide choice of materials are available with which to constructthe various components of the apparatus of the invention it will, ofcourse, be apparent that some of the solutions, particularly Xylene, areof a toxic and corrosive nature with respect to certain materials. Thechoice of material employed in constructing the processing chamber,solution containers, conduits, valves, and the like, should keep thesefactors in mind.

While the invention has been described primarily in terms of a lightmicroscopy tissue processing application, it will be apparent thatde-energization of the .[.heating.]. .Iadd.heated .Iaddend.paraffinsteps, elimination of the .[.cleaing.]. .Iadd.clearing .Iaddend.steps,and addition of a slide rack to the processing chamber, will render theprocessor highly suitable for use as an automatic mounted slide stainingapparatus.

In summarizing the advantages of the present invention tissue processingapparatus, it will be noted that a substantially closed fumeless andsimplified system has been provided for fixing, dehydrating, clearingand paraffin infusing light microscopy sized tissue in a relativelylarge quantity. Those skilled in the art will particularly recognize theadvantages of maintaining tissue in a stationary, sealed chamber duringprocessing. In addition, the selective application of partial vacuum andpressure to the processing chamber has the two-fold effect of providinga mechanism for fluid transfer as well as a means for enhancing fluidpenetration into the tissue.

The mounting of the air pump 61 and its associated piping and valves inthe cabinet provides a unitary and self-contained processing apparatuswith obvious advantages. However, it is recognized that the source ofvacuum and pressure conditions could be obtained by use of separateexternal laboratory vacuum and pressure supplies fitted with electricalvalves and leading direct to processing chamber 12. Also the controlscould be mounted in a separate cabinet. However, this also would tend todetract from the many advantages of unifying all the necessaryprocessing and control apparatus in a common table top mounted cabinet.Close valve coupling between the processing chamber and the one or moreheated paraffin containers is most desireable to provide heated paths ofminimal length to minimize the amount of heat required to keep theparaffin .Iadd.melted .Iaddend.in those fluid paths which necessarilycarry the paraffin back and forth to the processing chamber. Theparaffin containers should preferably be immediately adjacent theprocessing chamber and all fluid connections for the paraffin should beof minimal length for the reasons stated. Some separation can betolerated however, provided any interconnecting paraffin carrying pipesare sufficiently heated and such heat is insulated as required toprevent heating those solutions which should preferably not be heated.

What is claimed is:
 1. A closed processing system enabling a pluralityof individual specimens of tissue to be separately contained while beingbathed simultaneously for varying lengths of time in successive selectedtissue solutions including melted paraffin so as to fix, dehydrate andclear the specimens preparatory to embedding, comprising:a. a pluralityof uniform tissue receptacles each being adapted to contain andphysically isolate a group of tissue specimens having at least onespecimen per group, each receptacle having a body portion defining anopen cavity adapted to receive and retain specimens and closure meansremovably received by said body to enclose said cavity, the materialforming said receptacles being inert to all of said solutions and havingfor each of said solutions at least some portion through which each ofsaid solutions may be transferred; b. a cabinet; c. an electricallyheated, temperature controlled container mounted in said cabinet andhaving a movable cover and being adapted for melting and holding meltedparaffin; d. a plurality of closed solution containers mounted inpredetermined order in a storage compartment in said cabinet proximatesaid paraffin container, each solution container containing a particulartissue processing solution and with said melted paraffin containercollectively containing all of the said tissue solutions in which saidspecimens are processed; e. air pump means having associated remotelyelectrically controllable first valve means mounted proximate saidcabinet and associated interconnected piping means, said pump meansproviding a pressure and vacuum source and said first valve means beingselectively operable to connect said source whereby to produce aselected pressure or vacuum condition in said piping means; f. aprocessing chamber mounted in said .[.chamber.]. .Iadd.cabinet.Iaddend.and having an end wall immediately adjacent an end wall of saidmelted paraffin container, said chamber having a pressure sealable topcover and being adapted to receive and process therein selected numbersof said receptacles simultaneously.Iadd., .Iaddend.said chamber beingtemperature controlled and electrically heated and being connected tosaid piping means thereby enabling the corresponding selected pressureand vacuum condition in said piping means to be produced in saidchamber; g. a second remotely electrically controllable valve meansmounted in said cabinet and having on one side a fluid connection tosaid chamber and on the other side a fluid connection to said paraffincontainer enabling the paraffin contents thereof to be exchanged betweenthe chamber and said paraffin container, said fluid connections for saidsecond valve means being of minimal length and being electrically heatedand maintained at a temperature above the melting point of saidparaffin; h. a third remotely electrically controllable valve meansmounted in said cabinet and having on one side a fluid connection ofminimal length to said chamber and on the other side a port for transferof solutions therethrough; i. fourth remotely electrically controllablesolution transfer valve means positioned in said cabinet between saidprocessing chamber and said storage compartment, said fourth valve meansbeing fluid connected on one side to said third valve transfer port andon the other side having separate fluid connections to each of saidsolution containers and being remotely electrically controllable forenabling each solution container connection on the one side of thefourth valve means to be selectively and independently connected to saidtransfer port for a predetermined time while all other solutioncontainer connections are isolated therefrom and at other times toisolate all of said solution container connections from said transferport; j. an electrical power source; and k. remotely operable electricalcontrol means connected to said power source and mounted proximate saidchamber for remotely powering and electrically operating each of saidvalve means and temperature controls in a predetermined time sequenceprogram whereby with a selected number of said receptacles installed insaid chamber and said cover sealed on said chamber, said solutions andsaid paraffin are successively, selectively and independently drawn fromsaid solution and paraffin containers, are measured by timing thewithdrawal and admitted to said chamber under a vacuum condition in apredetermined volume, retained for predetermined times at apredetermined pressure and at the end of each processing step beingforced back to a respective said solution and paraffin container bypressure from said pump means source in a corresponding processingsequence such that selected of said solutions and said melted paraffinare separately and independently exchanged with each said group ofspecimens while maintaining said system closed, said paraffintransferred a minimal distance, and each said group physically isolated.2. In a system as claimed in claim 1 including:a. a second said heatedand temperature controlled paraffin container, said first and secondparaffin containers being laterally spaced and positioned immediatelyadjacent said chamber with said paraffin containers and chamber beingbelow and foward of said compartment containing said solution containersin said cabinet, and b. a .[.sixth.]. .Iadd.fifth .Iaddend.remotelycontrollable valve means closely connected to second paraffin containerand comparable in position and function to said second valve means forsaid first container thus enabling the melted paraffin contents ofeither said first or second paraffin container to be selectivelyexchanged with the chamber through a path of minimal distance.
 3. In asystem as claimed in claim 2 wherein said second and .[.sixth.]..Iadd.fifth .Iaddend.valve means are submerged in the respective saidfirst and second melted paraffin containers and in immediate proximityto the respective paraffin container bottom walls and proximate the endwalls separating the paraffin containers and chamber, said end wallshaving respective ports connected to the respective second and.[.sixth.]. .Iadd.fifth .Iaddend.valve means enabling the respectivemelted paraffin contents to be transferred directly and under remotecontrol between said paraffin containers and chamber through said ports.4. In a system as claimed in claim 1 wherein said fourth valve meanscomprises a remotely electrically controllable rotary type valve.
 5. Ina system as claimed in claim 1 wherein said .[.paraffin container.]..Iadd.processing chamber .Iaddend.temperature control comprises a twostage control for obtaining different degrees of heat in said.[.paraffin container.]. .Iadd.processing chamber .Iaddend.and saidcontrol means controls the energization of each such stage in a timedsequence.
 6. In a system as claimed in claim .[.2.]. .Iadd.4.Iaddend.wherein .[.each.]. said .[.paraffin container.]..Iadd.processing chamber .Iaddend.temperature control comprises a twostage control for obtaining different degrees of heat in said.[.paraffin container.]. .Iadd.processing chamber .Iaddend.and saidcontrol means controls the energization of each such stage in a timedsequence.
 7. In a system as claimed in claim 2 including in said cabineta pair of laterally spaced control circuitry compartments mounted onopposite ends of said storage compartment and having front wall membersthereon, said circuitry and compartments being adjacent and above therespective said paraffin containers and said control means havingmanually positionable controls mounted on said front wall members ofsaid control circuitry compartments.
 8. In a system as claimed in claim7 wherein said cabinet, including said paraffin and solution containers,said .[.chambers.]. .Iadd.chamber.Iaddend., pump, valves, and saidcontrol circuitry compartments, is assembled and movable as an integraltable top mounted processing unit.
 9. In a system as claimed in claim 1wherein said control means includes circuitry connected to cycle theapplication of vacuum and pressure conditions in said chamber.
 10. In asystem as claimed in claim 2 wherein said piping means is connected tosaid chamber at an upper sidewall position proximate said chamber cover,said second and .[.sixth.]. .Iadd.fifth .Iaddend.valve means arepositioned adjacent said paraffin containers proximate the bottom wallsthereof and immediately adjacent said chamber, said third valve means ispositioned externally of and in close proximity to the bottom wall ofsaid chamber and including means for electrically heating said thirdvalve means, said respective valve positions enabling relatively directshort paths to be established between the lower interior portion of saidchamber and the respective valves.
 11. A system as claimed in claim 1wherein said control means include adjustable timing means enabling saidpredetermined time of retention to be changed both with respect to allas well as selected ones of said container melted paraffins andsolutions.
 12. A system as claimed in claim 1 having fan exhaust andfume collection means adapted to allow during operation of said systemcontinuous withdrawal of solution fumes from the area surrounding saidchamber.
 13. In a system as claimed in claim 1 wherein said controlmeans is mounted on said cabinet and said air pump means comprises anelectrically operated air pump mounted in said cabinet and saidinterconnected piping means includes an outlet pipe in which saidpressure and vacuum conditions may be selectively produced, said outletpipe being connected to said chamber.
 14. A closed processing systemenabling a plurality of individual specimens of tissue to be separatelycontained while being bathed simultaneously for varying lengths of timein successive selected tissue solutions including melting paraffin so asto fix, dehydrate and clear the specimens preparatory to embedding,comprising:a. a plurality of uniform tissue receptacles each beingadapted to contain and physically isolate a group of tissue specimenshaving at least one specimen per group, each receptacle having a bodyportion defining an open cavity adapted to receive and retain specimensand closure means removably received by said body to enclose saidcavity, the material forming said receptacles being inert to all of saidsolutions and having for each of said solutions at least some portionthrough which each of said solutions may be transferred; b. a cabinetadapted for table top mounting and having in an elevated central andrearward position a plural solution container storage compartment and onthe ends of said storage compartment a pair of rearwardly disposedcontrol circuitry compartments having front wall members thereon; c. apair of electrically heated, laterally spaced, temperature controlledparaffin containers mounted in said cabinet below, forward and proximatesaid storage compartment, each container having a movable cover andbeing adapted for melting and holding melted paraffin.[., thetemperature control therefor comprising a two stage control forobtaining two levels of temperature therein.].; d. a plurality of closedsolution containers mounted in predetermined order in a storagecompartment in said cabinet proximate said paraffin container, eachsolution container containing a particular tissue processing solutionand with said melted paraffin container collectively containing all ofthe said tissue solutions in which said specimens are processed; e.electrically operated air pump means mounted within said cabinet andhaving associated remotely electrically controllable first valve means,interconnected piping means and an outlet pipe connected thereto, saidfirst valve means being selectively operable and in variousconfigurations with said piping means to produce either a pressure orvacuum condition in said outlet pipe; f. a processing chamber mounted insaid cabinet between and at the level of said paraffin containers andhaving end walls immediately adjacent respective end walls of saidmelting paraffin containers, said chamber having a pressure sealable topcover and being adapted to receive and process therein selected numbersof said receptacles simultaneously, said chamber being temperaturecontrolled and electrically heated and being connected proximate saidtop cover to said pump outlet pipe thereby enabling the correspondingselected pressure and vacuum conditions in said outlet pipe to beproduced in said chamber.[.;.]. .Iadd., the temperature control thereforcomprising a two stage control for obtaining two levels of temperaturetherein; .Iaddend. g. second and third remotely electricallycontrollable valve means mounted in said cabinet proximate the bottomand respective end walls of said chamber each having on one side aminimal length fluid connection to said chamber and on the other side aminimal length fluid connection to a said paraffin container, both saidfluid connections being electrically heated to a temperature above theparaffin melting point enabling the respective paraffin contents thereofto be exchanged directly and under remote control through.[.connection.]. .Iadd.connecting .Iaddend.heated paths of minimaldistance between the chamber and the respective said paraffincontainers; h. a fourth remotely electrically controllable valve meanshaving means for being electrically heated and temperature controlledand being mounted in said cabinet proximate the bottom wall of saidchamber and having on one side a minimal length fluid connection to saidchamber and on the other side a port for transfer of solutionstherethrough; i. fifth remotely electrically controllable solutionrotary transfer valve means positioned in said cabinet between saidprocessing chamber and said storage compartment, said fifth valve meansbeing connected on one side to said fourth valve transfer port and onthe other side having separate connections to each of said solutioncontainers and being remotely electrically controllable for enablingeach solution container connection on the one side of the fifth valvemeans to be selectively and independently connected to said transferport for a predetermined time while all other solution containerconnections are isolated therefrom and at other times to isolate all ofsaid solution container connections from said transfer port; j. anelectrical power source; k. remotely operable electrical control meansmounted in said circuitry compartments and having manually positonablecontrols mounted on said front wall members, said control means beingconnected to said source and being adapted for remotely powering andelectrically operating each of said valve means, said pump means andsaid paraffin container temperature controls in a predetermined timesequence program whereby with a selected number of said receptaclesinstalled in said chamber and said cover sealed on said chamber, saidsolutions and said paraffin are successively, selectively andindependently drawn from said solution and paraffin containers, measuredby timing the withdrawal and admitted to said chamber under a vacuumcondition in a predetermined volume, retained for predetermined times ata predetermined pressure at the end of each processing step being forcedback to a respective said solution and paraffin container by pressurefrom said pump means in a corresponding processing sequence such thatselected of said solutions and said melted paraffin are separately andindependently exchanged with each said group of specimens whilemaintaining said system closed and each said group physically isolated;and l. electrically operated fan exhaust and fume collection meansmounted proximate said chamber and providing continuous withdrawal ofsolution fumes from the area surrounding said chamber.